import io.reactivex.Observable;

public class C29 {
    public static void main(String[] args) {
        Observable.just("Alpha", "Beta", "Gamma", "Delta", "Epsilon")
                  .filter(s -> s.startsWith("Z"))
                  .switchIfEmpty(Observable.just("Zeta", "Eta", "Theta"))
                  .subscribe(i -> System.out.println("RECEIVED: " + i),
                             e -> System.out.println("RECEIVED ERROR: " + e));
    }

}
//EOP
